1. Field of the Invention
The present invention relates to a rotation support with improved thrust-bearing for rotors of pump electric motors, i.e., a new way of supporting the axial thrusts generated in the fluid circulation pumps in order to make the production easier and to make the use and maintenance functional.
More in particular the invention relates to a rotation support for pump motors comprising a stator of the electric motor, in which a hollow body is housed for supporting and containing a permanent magnet rotor, an impeller being kinematically coupled with a shaft of the electric motor, as well as opposite shaft supports, one of which is provided with axial thrust-bearing.
2. Description of the Related Art
As it is well known to the technicians in the field, fluid circulation pumps comprise an electric motor whose rotor is keyed to a shaft, which carries, kinematically connected with an end, the impeller of the pump.
The pumps can have impellers of various form and scope of propulsion of the treated fluid; in the case of impellers with curve vanes of the centrifugal type, the pulse given to the fluid generates an axial thrust due to the pressure gradient which generates between the suction and delivery areas of the impeller. For the conformation of the pump, exactly of the centrifugal type, the above areas are always placed with the suction area belonging to the impeller in axis with the rotation shaft and the delivery in an annular region external to the diameter of the impeller and coplanar thereto.
This arrangement generates an axial thrust acting on the impeller, resulting from the axial component of the difference between the pressure field exiting upstream and downstream the impeller, such as to approach the suction mouth of the impeller towards the conduit which feeds the fluid.
In the typology of the motor pumps for fluids at issue in the present invention, motor pumps are known wherein the electric motor is of the synchronous type and the permanent magnet rotor is housed in a hollow body within the stator pack and the windings. The pack with the windings is separated and insulated from the hollow body for ensuring the electrical insulation, but the rotor is housed inside the stator pack in a extractable way for allowing an easy assembly and possible extraction for the maintenance.
In the technique, supporting the rotor with supporting bushes of antifriction material is known: the bush on the impeller side also supports the axial thrust transmitted from the impeller to the rotor by means of the driving shaft. The contact between the axial abutment of the supporting bush and the rotor occurs by means of a thrust-bearing disk of hard, abrasion-resistant material inserted between said axial abutment and the side of the motor. This disk is normally placed by means of an annular seat inserted and made integral with the driving shaft: the seat and the disk are axially blocked on the shaft in a suitable position for centering the rotor on the stator.
This disk, in a realization of Askoll Holding S.r.l., the assignee of the present application, is preferably placed by means of an annular cup of elastic material provided with a central convexity for allowing the adaptation of the disk to the abutment of the bush. The cup is further provided with engaging toothed edge of the external edge of the thrust-bearing disk.
The assembly of the disk and of the cup is housed in a suitable chamber realized on the side of the rotor by means of an extension of the plastic skirt of the rotor itself.
Therefore, in the state of the art, the support of the axial thrusts is known by means of the interposition of a suitable element, exactly the thrust-bearing disk, and of further accessory parts such as the containing annular seat and/or the annular cup of elastic material.